1. Technical Field
The present invention relates to a color cathode ray tube (CRT), and more particularly to a tension mask frame assembly having an improved thermal compensation feature compensating for a mislanding of an electron beam.
2. Related Art
In a color cathode ray tube, three electron beams are emitted from an electron gun and land on fluorescent substances for red, green and blue colors coated on a fluorescent film formed on a screen surface of a panel via passing electron beam passing holes of a mask having a color selection function. The electron beams excite the fluorescent substances to form an image.
In the above color cathode ray tube forming an image, masks having a color selection function are classified as a dot mask adopted in a computer monitor or as a slot mask (or slit mask) used in a television.
A tension mask which is one of the slot masks, is supported by a frame to apply tension considering a screen surface which is flat so as to compensate for distortion of an image and to widen a viewing angle of a screen, and a lot of developments have been performed. A mask frame assembly, which supports a frame and a mask so that tension is applied by the frame, is installed in a panel of a color cathode ray tube.
A color cathode ray tube includes a panel having a screen surface that is flat and wherein a fluorescent film is formed, a tension mask frame assembly suspended on an inner surface of the panel, a funnel coupled to the panel forming a seal, where an electron gun is sealed in a neck portion, and a deflection yoke installed at a cone portion of the funnel.
A tension mask frame assembly includes a tension mask wherein a plurality of long slots are formed, support members for supporting corresponding edges of the tension mask, and elastic members for applying tension to the tension mask by supporting the respective end portions of the support members.
The tension mask frame assembly having the above structure attempts to compensate for mislanding of electron beams due to thermal expansion as it is heated by the electron beams that do not pass through the slots which are electron beam passing holes.
Exemplars of recent efforts in the art are disclosed, for example, in Japanese Publication Number 08-124489 to Imada et al., entitled COLOR SORTING DEVICE, published on May 17, 1996, Korean Patent Application No. 2001-1878 to Ha et al., entitled MASK-FRAME ASSEMBLY FOR COLOR CATHODE-RAY TUBE, filed on Jan. 12, 2001, U.S. patent application Ser. No.09/938,838 (Publication No. US-2002-0135286-A1) to Ha et al., entitled MASK-FRAME ASSEMBLY FOR COLOR CATHODE-RAY TUBE, published on Sep. 26, 2002, Korean Patent Application No. 2001-65365 entitled MASK FRAME ASSEMBLY AND COLOR CRT USING THE SAME, filed on Oct. 23, 2001, and U.S. patent application Ser. No. 10/269,075 entitled MASK FRAME ASSEMBLY AND COLOR CRT USING THE SAME. A structure of a panel of a tension mask frame assembly is disclosed in the Japanese Publication No. hei 8-124489.
While these contemporary efforts contain merit, it is our observation that further improvements can also be contemplated to more sufficiently compensate for movement due to thermal expansion and to achieve more improvements, including better color purity.